A linear conveyer including a slider that moves along a rail has been used. The slider is a platform car that conveys parts. Such a linear conveyer includes, for example, a unit-type stationary module and the slider. The stationary module includes a rail that extends linearly and a stator including armature coils and is fixed to the rail. The slider includes a rail guide that is fitted on the rail and a mover that faces the stator when the rail guide is fitted to the rail, and the mover includes powerful permanent magnets to generate magnetic poles.
Such a linear conveyer includes a linear scale that detects a position of the slider that moves along the rail. The linear scale includes a scale that is provided on the slider and a sensor that is provided on the stationary module. For example, a linear conveyer including a magnetic linear scale has been known. Such a magnetic linear scale includes a magnetic scale having magnets that is provided on the slider and a magnetic sensor that is provided on the module, and the magnetic linear scale detects a position of the slider according to magnetic flux from the magnetic scale.
The magnetic scale includes a back yoke and a plurality of neodymium magnets that are mounted on a surface of the back yoke. The neodymium magnets are bonded to the back yoke, for example. In such a magnetic scale, the neodymium magnet is used as the magnet. However, it is effective to use a plastic magnet as the magnet to reduce the weight of the scale and the slider.